lan9311 Standard Microsystems Corp., lan9311 Datasheet - Page 97

• Manufacturer Part Number: lan9311
• Description: Lan9311/lan9311i Two Port 10/100 Managed Ethernet Switch With 16-bit Non-pci Cpu Interface
• Manufacturer: Standard Microsystems Corp.

Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
SMSC LAN9311/LAN9311i
7.3.1.1
7.3.1.2
The emulated auto-negotiation process is much simpler than the real process and can be categorized
into three steps:
1. Bit 5 (Auto-Negotiation Complete) is set in the
2. Bit 1 (Page Received) is set in the
3. The auto-negotiation result (speed and duplex) is determined and registered.
The auto-negotiation result (speed and duplex) is determined using the Highest Common Denominator
(HCD) of the
Auto-Negotiation Link Partner Base Page Ability Register (VPHY_AN_LP_BASE_ABILITY)
specified in the IEEE 802.3 standard. The technology ability bits of these registers are ANDed, and if
there are multiple bits in common, the priority is determined as follows:
For example, if the full capabilities of the Virtual PHY are advertised (100Mbps, Full Duplex), and if
the link partner is capable of 10Mbps and 100Mbps, then auto-negotiation selects 100Mbps as the
highest performance mode. If the link partner is capable of half and full-duplex modes, then auto-
negotiation selects full-duplex as the highest performance operation. In the event that there are no bits
in common, an emulated
The
ability bits set. These values can be reconfigured via software. Once the auto-negotiation is complete,
any change to the
affect until the auto-negotiation process is re-run. The emulated link partner always advertises all four
abilities (100BASE-X full duplex, 100BASE-X half duplex, 10BASE-T full duplex, and 10BASE-T half
duplex) in the
(VPHY_AN_LP_BASE_ABILITY). Neither the Virtual PHY or the emulated link partner support next
page capability, remote faults, or 100BASE-T4.
If there is at least one common selection between the emulated link partner and the Virtual PHY
advertised abilities, then the auto-negotiation succeeds, the Link Partner Auto-Negotiation Able bit 0
of the
ability bits in the
(VPHY_AN_LP_BASE_ABILITY)
Note: For the Virtual PHY, the auto-negotiation register bits (and management of such) are used by
Parallel Detection
In the event that there are no common bits between the advertised ability and the emulated link
partners ability, auto-negotiation fails and emulated parallel detect is used. In this case, the Link
Partner Auto-Negotiation Able (bit 0) in the
(VPHY_AN_EXP)
technology ability bits in the
(VPHY_AN_LP_BASE_ABILITY)
Disabling Auto-Negotiation
Auto-negotiation can be disabled in the Virtual PHY by clearing bit 12 (VPHY_AN) of the
Basic Control Register
to reflect the speed (bit 13) and duplex (bit 8) of the
100Mbps Full Duplex (highest priority)
100Mbps Half Duplex
10Mbps Full Duplex
10Mbps Half Duplex (lowest priority)
(VPHY_BASIC_STATUS).
(VPHY_AN_EXP).
Virtual PHY Auto-Negotiation Advertisement Register (VPHY_AN_ADV)
Virtual PHY Auto-Negotiation Expansion Register (VPHY_AN_EXP)
the Host MAC. So the perception of local and link partner is reversed. The local device is the
Host MAC, while the link partner is the switch fabric. This is consistent with the intention of the
Virtual PHY.
Virtual PHY Auto-Negotiation Advertisement Register (VPHY_AN_ADV)
Virtual PHY Auto-Negotiation Link Partner Base Page Ability Register
will be cleared, and the communication set to 100Mbps half-duplex. Only one of the
Virtual PHY Auto-Negotiation Advertisement Register (VPHY_AN_ADV)
Virtual PHY Auto-Negotiation Link Partner Base Page Ability Register
(VPHY_BASIC_CTRL). The Virtual PHY will then force its speed of operation
Parallel Detection
Virtual PHY Auto-Negotiation Link Partner Base Page Ability Register
are set to indicate the emulated link partners abilities.
will be set, indicating the emulated parallel detect result.
DATASHEET
97
is used.
Virtual PHY Auto-Negotiation Expansion Register
Virtual PHY Auto-Negotiation Expansion Register
Virtual PHY Basic Status Register
Virtual PHY Basic Control Register
is set, and the technology
defaults to having all four
Revision 1.2 (04-08-08)
and
will not take
Virtual PHY
Virtual PHY
as